ES2657622T3 - Start valve for a fluid drive machine operating in a vacuum system - Google Patents

Abstract

A start valve (100) for a fluid drive machine (200) operating in a vacuum system (1000); wherein the starter valve (100) provides: - a valve body (10), which is provided with at least one opening (17) for allowing a gas to enter; and - an actuator piston (13) which is keyed in a rod (16), which can slide freely in guide means (18A); said actuator piston (13) defining a chamber (30) together with a portion of said valve body (10); said actuator piston (13) being subjected to the action of a deformable diaphragm (15), in which a through hole (16A) and a calibrated orifice (16B) of throttling are provided in series therewith, which extend longitudinally to through said rod (16); said holes (16A, 16B) establishing a fluid connection between said chamber (30) and a dynamic fluid line (500) of said vacuum system (1000); and wherein the start valve (100) additionally comprises a plug (20), which is also keyed in said rod (16); said shutter (20) being suitable for closing a gas passage opening (10B), depending on the difference in pressure between said chamber (30) and said dynamic fluid line (500); start valve characterized in that said calibrated choke hole (16B) and said through hole (16A) establish a fluid communication between the space enclosed by a connection (25) and a space (22), defined by a cover element (23 ) positioned in said valve body (10); and because said space (22) and said chamber (30) are in mutual fluidic communication, by means of an air passage (24).

Description

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DESCRIPTION

Start valve for a fluid drive machine operating in a vacuum system Technical field

The present invention relates to a start valve for a fluid drive machine operating in a vacuum system.

Additionally, the present invention relates to a vacuum system comprising the start valve mentioned above.

Background Technique

In the technique of circulation and compression of gas, in particular of air, it is quite common to use start valves that facilitate the start-up of compressors or blowers, in the presence of a back pressure at the outlet of the system.

The presence of said back pressure generates a load on the compressor, even with the machine stopped, consequently determining a sudden and high electricity requirement and, therefore, an overload at the start of the drive machine, such as to prevent its operation due to the high current absorption of the electric starter motor.

At present, there are start-up valves on the market that allow operation without load for a temporary period, which allows to correctly control the operation of compressors and blowers, avoiding unwanted overloads.

According to the operating pressure of the system and the volume of gas to be treated, the appropriate start valve is chosen.

The presence of such a start valve allows eliminating the start overload, equalizing the pressure between the compressor inlet and outlet, thus eliminating the pressure difference that would otherwise generate the high initial overload.

Immediately afterwards, the start valve closes progressively until it reaches its calibration value, which corresponds to the operating pressure of the entire system.

The gradual closure of the start valve allows a progressive load to be generated in the drive machine and, therefore, in the electric starter motor of the drive machine.

However, the currently commercialized start valves do not allow a degree of precision in the pressure adjustment, so that they can be applied successfully in both pressure and vacuum applications.

Therefore, the aim of the present invention is to conceive a start valve that has a precise adjustment of the high pressure, even in systems that include vacuum-operated fluid drive machines.

In order to produce this starter valve, the already consolidated construction criteria of simplicity and low cost of well-known pressure applications have been used.

The present start valve is particularly useful in all vacuum applications with a low expansion ratio (i.e., a relationship between atmospheric pressure and the absolute operating pressure of the system not exceeding 5) with high gas flow rates.

This starter valve, in addition to facilitating the start-up of the drive machines, guarantees the maintenance of a constant working pressure (± 1% of the required pressure), a factor that has proved to be essential for efficient and correct operation in This type of applications.

US-A-4 613 111 and US-A-4 785 852, separately, describe the preamble portion of claim 1.

Disclosure of the invention

Therefore, the main objective of the present invention is to provide a start valve that, in a vacuum system, prevents the drive machine from operating in conditions of excessive overload, thereby saving energy, or operating with values lower than those relative to the optimal operating conditions of the process.

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A further objective of the present invention is to provide a vacuum system comprising at least one start valve as mentioned above.

Therefore, according to the present invention there is provided a start valve, and a vacuum system that integrates said valve, in accordance with the respective independent claims or with any of the claims that depend directly or indirectly on the independent claims.

Brief description of the drawings

For a better understanding of the present invention, some preferred embodiments are now described, purely by way of non-limiting examples and with reference to the accompanying drawings, in which:

- Figure 1 illustrates a longitudinal section of a start valve, produced in accordance with the teachings of the present invention;

- Figure 2 shows a first configuration of a vacuum system, comprising a start valve of the type illustrated in Figure 1;

- Figure 3 illustrates a second configuration of a vacuum system, comprising a start valve of the type illustrated in Figure 1;

- Figure 4 shows a third configuration of a vacuum system, comprising a start valve of the type illustrated in Figure 1;

- Figure 5 illustrates a start valve of the type illustrated in Figure 1, associated with a related pilot valve; Y

- Figure 6 shows the start valve and the pilot valve of Figure 5, integrated in a vacuum system. Best way to carry out the invention

In figure 1 the number 100 indicates, as a whole, a start valve integrated in a vacuum system 1000 (figures 2, 3, 4).

In this regard, as illustrated in the accompanying figures 2, 3, 4, the vacuum system 1000 comprises, in addition to said start valve 100, a drive machine 200 located downstream of said start valve 100.

The vacuum system 1000 further comprises a check valve 300, located between the start valve 100 and a vacuum tool 400.

A dynamic fluid line 500 connects the vacuum tool 400, the check valve 300, the start valve 100 and the drive machine 200, positioned in series with respect to each other.

Figures 2, 3, 4 will be mentioned again later when the operation of the start valve 100 is described, in the context of the general operation of the vacuum system 1000 (see below).

As illustrated in greater detail in Figure 1, the start valve 100 comprises the following elements:

- a valve body 10;

- a cover 11;

- a plate 12 of an actuator piston 13; said actuator piston 13 can rest on the edge of an air passage opening 10A, which is inside the valve body 10; note that, even when the actuator piston 13 rests on the edge of the first air passage opening 10A, in said actuator piston 13 there is a hole 13A that is always open and always allows the passage of an air flow (F) , in all operating conditions of the valve 100;

- an annular locking nut 14;

- a deformable diaphragm 15, connected to the plate 12 and the actuator piston 13;

- a rod 16, on which the plate 12 is keyed by means of the locking ring nut 14;

- multiple openings 17, located in the valve body 10, through which the above-mentioned air flow (F) passes through the use, which comes from the external environment (see below);

- a central hub 18, supported by the valve body 10 by means of multiple spokes 19 (in figure 1 only two spokes 19 can be observed); the central hub 18 being provided with a central through hole 18A, through which the rod 16 passes through the use, which can freely slide inside said hole 18A along a central axis (Y) of symmetry, in a first direction (ARW1) down, or in a second direction (ARW2) up;

- a shutter 20, also keyed in the stem 16; said shutter 20 being provided with a seal 21, suitable for closing a second air passage opening 10B; additionally, the shutter 20 advantageously has the shape of a cup-shaped body, which comprises an integral bottom 20A with a cylindrical collar 20B provided with multiple through openings 20C; note that both the actuator piston 13 and the shutter 20 are keyed in the rod 16;

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- a through hole 16A, which extends longitudinally (along the axis (Y) mentioned above) through the stem 16, and comprising a bore 16B; said through hole 16A establishes a fluidic connection between the space enclosed by a connection 25 and a space 22, defined by a cover 23 located at the top of the valve body 10; additionally, note that the cover 11 is provided with an air hole 24 (in the form of a circular crown) that establishes a fluidic connection between the space 22 and a chamber 30, located below, which is defined at the top by the cover 11, in the lower part by the assembly consisting of the plate 12 and the deformable diaphragm 15, and centrally by the substantially cylindrical surface of the rod 16; additionally, as illustrated in Figure 1, the upper end of the rod 16 can slide freely in the space 22; additionally, an annular nut 35 is attached to the upper end of the stem 16 which, in a particular configuration of the system, is used to limit the opening of the valve; Y

- a helical spring 40 having an upper end 40A, resting on the spokes 19, and a lower end 40B resting on the upper surface of the bottom 20A; therefore, the shutter 20 is subject to a first action transmitted thereto by the rod 16, and to a second elastic action imparted by the helical spring 40 (see below).

Although in Fig. 1 the openings 20C have a triangular shape, for reasons of simplicity, said openings 20C can have different shapes and sizes (semicircular, square, rectangular, etc.) so that the air flow passage area increases further or less progressively, depending on the movement of the stem 16.

This particular feature allows the operation of the present valve to be adapted to a wider operating field, in a simple and effective way.

Note that connection 25 is used to hydraulically connect valve 100 to dynamic fluid line 500 (Figures 2, 3, 4).

The operation of the start valve 100 will be described below, with reference also to the diagrams of the vacuum system 1000 presented in Figures 2, 3, 4:

- in the initial configuration of the start valve 100, shown on the left side of figure 1, the shutter 20 does not rest on the edge of the opening 10B, and the drive machine 200 (figure 2) is stopped; therefore, in this initial configuration, the coil spring 40 keeps the start valve 100 open;

- when the drive machine 200 is activated (Figure 3), external air is drawn from the outside environment through the openings 17 (arrow (F)), which flows through the through holes 20C; this causes a pressure drop through the through openings 20C located in the collar 20B of the shutter 20, thereby inducing the closure of the start valve 100 in an adjustable time;

- the pressure drop generated in the shutter 20 is slowly propagated through a calibrated throttle hole 16B, and the through hole 16A, to the chamber 30 (through the hole 24) located above the actuator piston 13; this causes a difference in the forces between the two sides of the actuator piston 13, due to the difference in the surfaces on which the vacuum acts; said force causes the movement of the actuator piston 13, upwards (arrow (ARW2)), further increasing the pressure drop and consequently increasing the force that causes the upward movement (arrow (ARW2)) of the actuator piston 13, until the start valve 100 is completely closed due to the fact that the gasket 21 now rests on the edge of the opening 10B (see the right side of Figure 1); This concludes the start-up phase of the drive machine 200 (Figure 4).

Advantageously, but not necessarily, the through hole 16A has a diameter greater than or equal to 1 mm (in particular 2 mm), while the calibrated choke hole 16B has a diameter ranging from 0.10 mm to 3 mm (in particular 0.20 mm).

During operation of the drive machine 200, the start valve 100 (Figure 4) remains closed, due to the difference between the forces generated by the same pressure acting on the different surfaces of the actuator piston 13 and the shutter 20.

When the drive machine 200 stops, due to the closing of the dynamic fluid line due to the presence of the check valve 300, located upstream of the start valve 100 (see Figure 2), the atmospheric pressure is restored below of the shutter 20 and, through the calibrated orifice 16B and the orifice 16A, the atmospheric pressure is also restored in the chamber 30.

At this time, the force of the spring 40, which is no longer counteracted by the forces induced by the voids, causes the start valve 100 to open (pushing the shutter 20 down; arrow (AWR1)), returning to the configuration initial shown on the left side of figure 1, ready to start over.

To adjust the closing time of the starter valve 100, the position of the ring nut 35 must be adjusted.

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By tightening the ring nut 35 around the rod 16, the plug 20 is moved closer to the opening 10B (in its initial configuration shown in the left part of Figure 1), reducing the closing time of the start valve 100; by loosening the ring nut 35, the plug 20 moves away from the opening 10B, proportionally increasing the closing time of the starter valve 100.

During operation of the drive machine 200, there is a need to precisely maintain or limit the vacuum required by the system, and this can be done by combining the start valve 100 described above with a control device 600 (figures 5, 6), which is described below.

The control device 600 is obtained using a direct acting pressure limiting valve, which is installed in the cover 11 of the starter valve 100 (Figure 5).

The control device 600 detects the operating depression of the vacuum system 1000, by means of a pressure fitting 601 located at the connection 25 (Figure 5), or directly on the dynamic fluid line 500.

Therefore, the control device 600 reacts to vacuum variations, in turn varying the flow of atmospheric air to the chamber 30 of the start valve 100.

If, for example, the depression of the vacuum system 1000 increases, the control device 600 detects the pressure variation by means of a diaphragm 602, which is subjected, on the one hand, to atmospheric pressure through a hole 603 , and, on the other hand, to the depression of the vacuum system 1000 through a conduit 604.

The pressure difference on the diaphragm 602 causes a shutter 605 to move in the direction of an arrow (ARW3) (Figure 5). In its movement, the shutter 605 compresses a spring 606.

The movement of the shutter 605 establishes a communication, through a through hole 607, between the external environment at atmospheric pressure and the chamber 30 of the starter valve 100, through two connections 608, 609 (Figure 5).

Consequently, the pressure of the chamber 30 increases, causing the shutter 20 of the starter valve 100 to move down (in the direction of the arrow (ARW1)), thereby increasing the amount of air entering the vacuum system through the openings 17 of the start valve 100, until a new equilibrium condition is reached.

If the depression of the vacuum system falls, the behavior of the control device 600 and the start valve will be exactly opposite to that just described, reducing the admission of atmospheric air from the orifice 607, until a New equilibrium condition.

The main advantages of the start valve according to the invention can be summarized in the following points:

- operation without load is guaranteed for vacuum applications, in order to limit the maximum energy absorption in the irruption phase, during commissioning of the drive machine; This new mechanical configuration of the valve allows a greater precision in the opening of the valve, prevents the drive machine from operating in conditions of excessive overload, with the consequent energy saving, or that it operates with values lower than those relative to the conditions optimal operations of the process;

- a constant operating pressure of the system can be guaranteed with high precision (± 1% of the required pressure), thanks to the use of an appropriate control element, if necessary;

- the actuation function is combined with the sealing function for negative pressures in the same mechanical element (these functions are normally separated in the valves currently marketed); this avoids the usual construction complications;

- the possibility of integrating an element to seal the flow, due to the configuration of the present valve, to thus extend the field of application of the valve to a wider than normal operating field, both for vacuum and pressure applications, avoiding the operational instability that currently occurs in the presence of significant reductions in flow (30% of nominal flow), in the valve and in the system as a whole; Y

- The number of component elements of the valve has been reduced, by adopting a direct-acting actuator system, with a single operating pressure chamber, unlike double-acting systems and double-chamber systems present in the market.

Claims (9)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 1. A start valve (100) for a fluid drive machine (200) operating in a vacuum system (1000); in which the start valve (100) provides: - a valve body (10), which is provided with at least one opening (17) for allowing a gas to enter; Y - an actuator piston (13) which is keyed in a rod (16), which can slide freely in guide means (18A); said actuator piston (13) defining a chamber (30) together with a portion of said valve body (10); said actuator piston (13) being subjected to the action of a deformable diaphragm (15), in which a through hole (16A) and a calibrated orifice (16B) of throttling are provided in series therewith, which extend longitudinally to through said rod (16); said holes (16A, 16B) establishing a fluid connection between said chamber (30) and a dynamic fluid line (500) of said vacuum system (1000); and wherein the start valve (100) additionally comprises a plug (20), which is also keyed in said rod (16); said shutter (20) being suitable for closing a gas passage opening (10B), depending on the difference in pressure between said chamber (30) and said dynamic fluid line (500); start valve characterized in that said calibrated choke hole (16B) and said through hole (16A) establish a fluid communication between the space enclosed by a connection (25) and a space (22), defined by a cover element (23 ) positioned in said valve body (10); and because said space (22) and said chamber (30) are in mutual fluidic communication, by means of an air passage (24). 2. The start valve (100) according to claim 1, characterized in that said through hole (16A) has a diameter greater than or equal to 1 mm (in particular 2 mm), while the calibrated orifice (16B) of throttle It has a diameter that varies from 0.10 mm to 3 mm (in particular 0.20 mm). 3. Start valve (100) according to any of the preceding claims, characterized in that said shutter (20) is subject to elastic forces generated by an elastic element (40). 4. A start valve (100) according to any of the preceding claims, characterized in that said shutter (20) is advantageously configured as a cup-shaped body, and comprises a bottom (20A), with which it is integrated a cylindrical collar (20B), which is provided with multiple through openings (20c). 5. A start valve (100) according to claim 4, characterized in that said openings (20C) have different shapes and sizes (triangular, semicircular, square, rectangular, etc.), such that the passage area of the Air flow increases more or less progressively depending on the movement of said rod (16). A starter valve (100) according to claim 5, characterized in that one end of said rod (16) can slide freely through said space (22). 7. A start valve (100) according to claim 6, characterized in that said end of said stem (16) is fixed to an annular nut (35), which is used to limit the opening of the start valve ( 100). 8. A start valve (100) according to any of the preceding claims, characterized in that it comprises fluid connection means (601, 608, 609) for connection to a control device (600), which reacts to variations of vacuum by directly varying the flow of atmospheric air to said chamber (30). 9. A vacuum system (1000), comprising at least one start valve (100) according to any one of claims 1 to 8.